Device for treating a bottom-hole formation wellbore

ABSTRACT

A device for treating a bottom-hole formation of a wellbore comprises a firing head and seal block assembly at a proximal end thereof and a bullnose assembly at a distal end thereof. A carrier tube extends between the firing head and seal block assembly and the bullnose assembly. The carrier tube contains a combustible chemical composition which generates hydrochloric acid gas or hydrofluoric acid gas or a combination thereof when combusted. A dispersion tube extends from the carrier tube. The dispersion tube has a lateral opening. The lateral opening may be a slot or an aperture. There is a charge wire electrically connecting the firing head and sealing block assembly to the combustible chemical composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 of International Patent Application Number PCT/CA2019/050970, filed on Jul. 12, 2019, the disclosure of each of which is incorporated herein by reference and on each of which priority is hereby claimed.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a device for treating a wellbore and, in particular, to a device which generates hydrochloric acid gas, hydrofluoric acid gas or a combination thereof to treat a bottom-hole of a wellbore.

Description of the Related Art

It is known that a decrease in the permeability of a bottom-hole formation of a wellbore may result in a decrease in hydrocarbon recovery. The decrease in the permeability of the bottom-hole formation may be the result of dilatation due to asphaltic deposits or volumetric readjustments of bore space structure. Alternatively, the decrease in the permeability of the bottom-hole formation may be the result of clogging from clay swelling or deposits of foreign matter such as mechanical impurities, filtrates, well knitting, drill-in fluids, well development fluids, and cement. Sand and paraffin-hydrate plugs are also known to cause a decrease in the permeability of the bottom-hole formation as are calcium carbonate scale, calcium sulfate scale, and other scale. It is therefore desirable to treat the bottom-hole formation of a wellbore to increase the permeability of a bottom-hole formation and increase hydrocarbon recovery.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved device for treating a bottom-hole formation of a wellbore.

There is accordingly provided a device for treating a wellbore. The device comprises a firing head and seal block assembly at a proximal end thereof and a bullnose assembly at a distal end thereof. A carrier tube extends between the firing head and seal block assembly and the bullnose assembly. The carrier tube contains a combustible chemical composition which generates hydrochloric acid gas or hydrofluoric acid gas or a combination thereof when combusted. A dispersion tube extends from the carrier tube. The dispersion tube has a lateral opening. The lateral opening may be a slot or an aperture. There is a charge wire electrically connecting the firing head and sealing block assembly to the combustible chemical composition.

The combustible chemical composition may comprise between 30% and 60% by weight hexachloroethane and between 40% and 70% by weight ammonium nitrate. The combustible chemical composition may alternatively comprise between 30% and 60% by weight polyvinyl chloride and between 40% and 70% by weight ammonium nitrate. The combustible chemical composition may still alternatively comprise between 0% and 5% by weight polyvinyl chloride, between 25% and 55% by weight hexachloroethane, and between 40% and 70% by weight ammonium nitrate. The combustible chemical composition may still yet alternatively comprise between 5% and 25% by weight polytetrafluoroethylene, between 25% and 55% by weight hexachloroethane, and between 40% and 70% by weight ammonium nitrate.

The combustible chemical composition may be disposed in a sleeve. The sleeve may be a polyvinyl chloride sleeve. The combustible chemical composition may include a plurality of solid puck shaped members. The combustible chemical composition may further include an adhesive binding adjacent ones of the solid puck shaped members. The combustible chemical composition may further include a combustion catalyst.

BRIEF DESCRIPTIONS OF DRAWINGS

The invention will be more readily understood from the following description of the embodiments thereof given, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is an elevation, partially sectional, view showing a device for treating a bottom-hole formation of a vertical wellbore;

FIG. 2 is an exploded, perspective view of the device for treating a bottom-hole formation of a wellbore shown in FIG. 1;

FIG. 3 is an elevation, fragmentary and partially sectional, view of the device for treating a bottom-hole formation of a wellbore shown in FIG. 1;

FIG. 4 is an exploded, perspective view of another device for treating a bottom-hole formation of a wellbore; and

FIG. 5 is an exploded, perspective view of still another device for treating a bottom-hole formation of a wellbore.

DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

Referring to the drawings and first to FIG. 1, there is shown a device 10 for treating a bottom-hole formation 12 of a wellbore 14. The device 10 is lowered into the wellbore 14 by a wireline 16 in this example. However, in other examples, coiled tubing or other suitable means may be employed to lower the device 10 into the wellbore 14. The wellbore 14 is cased with a perforated casing 18. Gas generated by the device 10 to treat the bottom-hole formation 12 of the wellbore 14 flows through perforations in the perforated casing 18, for example, perforations 20 a and 20 b of the perforated casing 18, into corresponding perforations in the bottom-hole formation 12, for example, perforations 22 a and 22 b of the bottom-hole formation 12, as indicated generally by arrows 24 a and 24 b. It will be understood by a person skilled in the art that the device 10 may also be employed to treat a wellbore provided with a slotted liner or an open hole wellbore. It will also be understood by a person skilled in the art that the device 10 may be deployed in a vertical wellbore or horizontal wellbore. It will further be understood by a person skilled in the art that the device may be deployed in a producing wellbore or an injection wellbore.

The device 10 is shown in greater detail in FIG. 2. The device 10 comprises a firing head and sealing block assembly 30 at a proximal end thereof and a bullnose assembly 32 at a distal end thereof. A proximal end of a spacer tube 34 is coupled to the firing head and sealing block assembly 30. A carrier tube 36 is coupled to a distal end of the spacer tube 34. A dispersion tube 38 is coupled to a distal end of the carrier tube 36. A distal end of the dispersion tube is coupled to the bullnose assembly 32. There is a plurality of openings in the dispersion tube 38 which, in this example, are in the form of slots 40 a and 40 b.

The carrier tube 36 contains a combustible chemical composition which generates hydrochloric acid gas or hydrofluoric acid gas or a combination thereof when combusted. FIG. 3 shows a combustible chemical composition 42 contained in the carrier tube 36. In this example, the combustible chemical composition 42 is contained in the carrier tube 36 and comprises a plurality of puck shaped members, for example, puck shaped member 44 a and 44 b which are fitted into the carrier tube 36. There may be epoxy lining an inner surface of carrier tube 36.

A charge wire 46 provides a charge to combust the combustible chemical composition 42 contained in the carrier tube 36. In this example, at least one of the puck shaped members is a combustion catalyst comprising epoxy resin, potassium dichromate, and ammonium nitrate. However, it will be understood by a person skilled in the art that a combustion catalyst is not required, but any suitable combustion catalyst may be employed. The hydrochloric acid gas or hydrofluoric acid gas or a combination thereof, generated when the combustible chemical composition 42 contained in the carrier tube 36 flows into the dispersion tube 38 through the slots 40 a and 40 b in the dispersion tube 38.

Examples of the combustible chemical compositions are set out below. Examples 1-3 and 5-7 generate hydrochloric acid gas and examples 4 and 8 generate hydrochloric acid gas and hydrofluoric acid gas.

EXAMPLE 1

Component Percent by Weight Hexachloroethane 30% to 60% Ammonium nitrate 40% to 70%

EXAMPLE 2

Component Percent by Weight Chlorinated polyvinyl chloride 30% to 60% Ammonium nitrate 40% to 70%

EXAMPLE 3

Component Percent by Weight Chlorinated polyvinyl chloride 0% to 5% Hexachloroethane 25% to 55% Ammonium nitrate 40% to 70%

EXAMPLE 4

Component Percent by Weight Polytetrafluoroethylene  5% to 25% Hexachloroethane 25% to 55% Ammonium nitrate 40% to 70%

EXAMPLE 5

Component Percent by Weight Hexachloroethane 30% to 60% Ammonium nitrate 40% to 70% Potassium Dichromate 2% and 12%.

EXAMPLE 6

Component Percent by Weight Chlorinated polyvinyl chloride 30% to 60% Ammonium nitrate 40% to 70% Potassium Dichromate 2% and 12%.

EXAMPLE 7

Component Percent by Weight Chlorinated polyvinyl chloride 0% to 5% Hexachloroethane 25% to 55% Ammonium nitrate 40% to 70% Potassium Dichromate 2% and 12%.

EXAMPLE 8

Component Percent by Weight Polytetrafluoroethylene  5% to 25% Hexachloroethane 25% to 55% Ammonium nitrate 40% to 70% Potassium Dichromate 2% and 12%.

It will be understood by a person skilled in the art that the device 10 may also be employed to treat a wellbore provided with a slotted liner or an open hole wellbore. It will also be understood by a person skilled in the art that the device 10 may be deployed in a vertical wellbore or horizontal wellbore. It will further be understood by a person skilled in the art that the device may be deployed in a producing wellbore or an injection wellbore. A perforating gun may be used with the device 10. Packers may also be employed to isolate the devices.

FIG. 4 shows another device 50 for treating a bottom-hole formation of a wellbore. The device 50 is substantially similar to the device shown in FIGS. 1 to 3 with the notable exception that the dispersion tube 52 has lateral openings in the form of apertures 54 a and 54 b. FIG. 5 shows still another device 60 for treating a bottom-hole formation of a wellbore. The device 60 is substantially similar to the device shown in FIGS. 1 to 3 with the notable exception that there is no dispersion tube and the carrier tube 62 has lateral openings in the form of apertures 64 a and 64 b.

It will be understood by a person skilled in the art that many of the details provided above are by way of example only, and are not intended to limit the scope of the invention which is to be determined with reference to the following claims. 

What is claimed is:
 1. A device for treating a bottom-hole formation of a wellbore, the device comprising: a firing head and seal block assembly at a proximal end thereof; a bullnose assembly at a distal end thereof; a carrier tube extending from the firing head and seal block assembly the carrier tube containing a combustible chemical composition which generates hydrochloric acid gas or hydrofluoric acid gas or a combination thereof when combusted; a dispersion tube extending from the carrier tube, the dispersion tube having a lateral opening; and a charge wire electrically coupling the firing head and sealing block assembly to the combustible chemical composition.
 2. The device as claimed in claim 1 wherein the lateral opening in the dispersion tube is a slot.
 3. The device as claimed in claim 1 wherein the lateral opening in the dispersion tube is an aperture.
 4. The device as claimed in any one of claims 1 to 3 wherein the combustible chemical composition comprises between 30% and 60% by weight hexachloroethane and between 40% and 70% by weight ammonium nitrate.
 5. The device as claimed in any one of claims 1 to 3 wherein the combustible chemical composition comprises between 30% and 60% by weight polyvinyl chloride and between 40% and 70% by weight ammonium nitrate.
 6. The device as claimed in any one of claims 1 to 3 wherein the combustible chemical composition comprises between 0% and 5% by weight polyvinyl chloride, between 25% and 55% by weight hexachloroethane, and between 40% and 70% by weight ammonium nitrate. The device as claimed in any one of claims 1 to 3 wherein the combustible chemical composition comprises between 5% and 25% by weight polytetrafluoroethylene, between 25% and 55% by weight hexachloroethane, and between 40% and 70% by weight ammonium nitrate.
 8. The device as claimed in any one of claims 1 to 3 wherein the combustible chemical composition further comprises between 2% and 12% by weight potassium dichromate.
 9. The device as claimed in any one of claims 1 to 3 wherein the combustible chemical composition includes a plurality of puck shaped members.
 10. The device as claimed in claim 9 wherein the combustible chemical composition further includes an adhesive binding adjacent ones of the puck shaped members.
 11. The device as claimed in claim 9 wherein the combustible chemical composition further includes a combustion catalyst. 